Pivoting link safety latch

ABSTRACT

Safety latch has a latch mechanism securable to a door which cooperates with a latchplate securable to a doorframe, or vice versa, to limit the opening of the door. The safety latch has a body secured to the door, an intermediate link pivoted thereto, and an outer link pivoted to the intermediate link. A latch is movably mounted upon the outer link to selectively engage with the latchplate. When engaged, the links can fold outwardly from the base to permit the door to open, but only a limited extent.

United States Patent [191 Markovitch Dec. 9, 1975 PIVOTING LINK SAFETYLATCH Branko Markovitch, Hawthorne, Calif.

[73] Assignee: Samuel P. Simmons, Lomita, Calif.

[22] Filed: Jan. 24, 1974 [21] Appl. No.: 436,098

[75] Inventor:

[52] U.S. Cl. 292/283 [51] Int. Cl. E05C 19/08 [58] Field of Search292/114, 262, 275, 338, 292/283 [56] References Cited UNITED STATESPATENTS 526,164 9/1894 Phelps 292/263 1,942,665 l/l934 Schmitt 292/2631,961,472 6/1934 Abrahams 292/263 1,988,237 l/1935 Chisling 292/2632,407,900 9/1946 Paul 70/93 2,758,343 8/1956 Turner 292/263 X 3,499,6753/1970 lsenberg 292/278 X Primary Examiner-Richard E. Moor Attorney,Agent, or Firm-John Holtrichter, Jr.

[57] ABSTRACT Safety latch has a latch mechanism securable to a doorwhich cooperates with a latchplate securable to a doorframe, or viceversa, to limit the opening of the door. The safety latch has a bodysecured to the door, an intermediate link pivoted thereto, and an outerlink pivoted to the intermediate link. A latch is movably mounted uponthe outer link to selectively engage with the latchplate. When engaged,the links can fold outwardly from the base to permit the door to open,but only a limited extent.

10 Claims, 15 Drawing Figures us. Patent D;c.9,1975 sheetlofz. 3,924,887

US. Patent Dec.9, 1975-' sh etz fz 3,924,887

Fig.12. Fig. 15.

PIVOTING LINK SAFETY LATCH BACKGROUND OF THE INVENTION This invention isdirected to a safety latch for fastening to a door to permit the door tobe opened a limited distance.

When the security of person or property is involved, door locks andlatches are required. Many types of further objects and'advantagesthereof, may best be unlocks have been created to retain doors in closedposition, except at the manipulation of the owner. In addition, thereare a number of reasons why it is desirable for a door to be permittedto swing open a limited amount and prevented from swinging further open.Such limited swinging permits ventilation without access and permitsinspection outward through the limited door opening also without access.Accordingly, a number of structures have been created for stopping adoor from fully opening.

For the most part, these prior artstructures comprise a chain fixed atone end and detachably securable at the other end for connection betweenthe door and the structure ajacent the door. Some of the disadvantagesinclude a difficulty in manipulation, a weakness of the total structurewhere the weak point is usually found in the end attachment, and thefact that the end attachment on the doorframe side is usually attachedto the door trim rather than a structural part; therefore they are notas reliable and strong as might be desired.

SUMMARY OF THE INVENTION In order to aid in the understanding of thisinvention,

it can be stated in essentially summary form that it is directed to asafety latch which permits limited opening of a door, with maximumsecurity. The safety latch comprises a base securable to the door, withan intermediate like pivoted to the base and an outer link pivoted tothe intermediate link. The outer link movably carries a latch which isengageable with a latchplate securable to the doorframe. However, incertain situations the positions of the latchplate and base may beinterchanged.

It is thus an object to provide a safety latch which is economic ofconstruction and is easy to use so that it may be used by the generalpopulace for safety and convenience.

It is another object of this invention to provide a safety latch whichengages between the door-mounted latch portion and the latchplate byturning a knob which engages the latch nose with the latchplate andpermits the structure to unfold to limit the door opening to the lengthof the unfolded latch structure.

It is a further object to provide a safety latch with an outer linkpivoted to an intermediate link which, in turn, is pivoted to a basewhich is securable to the door and has a latch which is movably mountedon the outer link for engagement with the latchplate.

It is still another object to provide a safety latch structure which islocked into a folded configuration against the door until it is used. It

It is yet a further object to provide a safety latch which is used byturning a knob which extends a latch nose to engage with the latchplateand, at the same time, unlock the safety latch mechanism from its base.The features of the present invention which are beheved to be novel areset forth with particularity in the appended claims. The presentinvention, bothas to its organization and manner of operation, togetherwith tion, taken in conjunction with the accompanying drawings, in whichlike reference characters refer to like elements in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front-elevational view ofthe preferred embodiment of the safety latch of this invention shown inthe folded and locked position;

FIG. 2 is a top-plan view thereof showing the door and a portion of thedoorframe in section;

FIG. 3 is a section theretlhrough taken generally along the line 3-3 ofFIG. 1;

FIG. 4 is a front elevation of the latch similar to FIG. 1 showing thelatch in an out-folded position with the latch nose in the engagedposition;

FIG. 5 is a rear view of the safety latch, as seen in FIG. 4;

FIG. 6 is a front-elevational view of another embodiment of the safetylatch of this invention shown in the folded and locked position;

FIG. 7 is a view thereof with. the safety latch mechanism of FIG. 6partly unfolded and with parts broken away and parts shown in section,

FIG. 8 is a bottom view of the outer link with parts broken away of theembodiment of FIG. 6;

FIG. 9 is a top-plan view of still another embodiment of the safetylatch of this invention showing the latch in its folded, but unlockedposition;

FIG. 10 is a side-elevational view thereof showing the safety latchmechanism in a partly unfolded position;

FIG. 11 is a bottom-plan view of the outer link structure and a portionof the intermediate link structure of the safety latch of FIGS. 9 and10;

FIG. 12 is a front-elevational view of a further embodiment of thesafety latch structure of this invention, particularly showing it inassociation with a base which incorporates a conventional doorknob anddoorlatch structure;

FIG. 13 is an elevational view of the latchplate employed with thesafety latch of FIG. 12;

FIG. 14 is a partial view showing the safety latch of FIG. 12 in theunfolded, extended position; and

FIG. 15 is'a rear view of the structure of FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 through 5 illustrate anembodiment 10 of the safety latch. Safety latch 10 comprisesabase-mounted portion 14 for mounting upon a door 12 and a latchplatestructure 16 for mounting upon doorframe l8. Latchplate 16 has a flat,substantially planar portion 19 for surface-mounting or recess-mountingin the doorjamb. The inward end of latchplate 16, that is the endextending toward the interior of the room, has a rolled edge 20 in theform of a cylindrical tube. The side of the cylindrical tube facing thebase-mounted portion 14 has an opening 21 therein in the shape of thecrossbar of a tee. The stem of the tee extends around the front of therolled edge, and a portion of it is seen at 22 in FIG. 1. The tee slotthus is wrapped around about of rollededge 20. The tee slot is forengagement by the safety latch.

FIGS. 2 and 3 illustrate the base-mounted portion 14 in the folded andlocked position. FIGS. 4 and 5 illustrate the same structure in theunfolded position, as if lying on a flat surface. Base-mounted portion14 comprises base 24 which has suitable screwholes 26 for secureattachment of base 24 onto door 12. Base 24 has upturned flange edges 28and 30. These flanged edges have a pivot pin hole at the end of the basetoward the door edge, and pivot pin 32 extends through this hole.

Intermediate link 34 has a rolled end 36 thereon which embraces pivotpin 32. At its other end, it has a rolled end 38 which embraces pivotpin 40. Outer link 42, particularly see FIG. 5, has downturned flangeedges 44 and 46. Pivot pin 40 passes through these downturned flanges tothat the base and the two links are pivoted together foraccordion-folding and expansion. As is seen in FIG. 2, the edge flanges28,30 and 44,46 are complementary so that they can lie together when thebase-mounted portion 14 of the safety latch is in the folded, lockedposition.

Disc 48 is positioned under outer link 42 and is rotated by knob 50through a shaft 51 of square crosssection, which disc extends above theother link to be manually accessible when the safety latch is locked inthe folded position. Latch disc 48 has tee 52 on one segment thereof.Adjacent the tee, latch disc 48 is provided with latch tongue 54. Ifdesired, another latch tongue 56 is positioned opposite latch tongue 54;however one side 58 of latch disc 48 is flat, as seen in FIG. 5.

Latch disc 48 has three functions. First, when the flat side 58 of thelatch disc is turned toward latchplate 16, the door is free to openunrestrained by safety latch 10. In this position of latch disc 48, itstee edge 52 engages into a slot 59 in a base-mounted lock post 60, seeFIG. 3, to hold the intermediate and outer links 34 and 42 in alocked-down, folded position. This is the position seen in FIGS. 1 and3. In its second function, with door 12 closed, latch disc 48 is turneda quarter turn so that either latch tongue 54 or 56 engages into thecrossbar of the tee slot 21 in latchplate 16. Outer link 42 is stilllocked down, because the opposite latch tongue remains in the slot 59 inlock post 60. In this position, the door cannot be opened at all; thussafety latch serves as a regular lock to hold the door in full closedposition, as illustrated in FIG. 2.

In its third function, as best illustrated in FIGS. 4 and 5, latch disc48 of the safety latch 10 is turned so that its tee 52 is engaged in thetee slot 21 in latchplate 16. In this position, flat side 58 is towardlock post 60 and thus the outer and intermediate links are unlocked fromthe base 24; however tee 52 is engaged in the stem portion 22 of the teeslot 21 in the latchplate 16. Now, when door 12 is swung open, outerlink 42 and intermediate link 34 hinge outward to permit the door toopen partway. With one end of the intermediate link pivoted on base 24and the tee 52 locked into the tee slot 21 in the latchplate, the linksunfold and limit the opening of the door. Thus limited opening securityis achieved.

The strength of the safety latch structure is substantial because thelatchplate 16 is secured to the strong part of the doorframe, and thebase-mounted portion 14 is sturdy and securely attached. With the door.12 returned to the closed position, the links fold up and then knob 50can be turned to swing either one of the latch tongues 54,56 or the flatside 58 toward the latchplate 16. This swings the tee 52 out ofengagement and locks the outer link 42down.

In order to allow the intermediate link 34 to fold down withoutengagement with the lock post 60, a hole 61 of relatively largerdiameter is provided in the intermediate link. Also, the latch disc 48is detented in its 4 various positions by a a-shaped spring S encirclingthe square cross-sectional shaft 51 and anchored by a short outerlink-mounted post P, as shown in FIG. 5.

FIGS. 6 through 8 illustrate safety latch 62 which is a presentlypreferred embodiment of the safety latch of this invention. Safety latch62 has the same base 64, intermediate link 66, and outer link 68 assafety latch 10. The latch structure is slightly different in thisspecies and comprises a sliding latch 70 positioned for sliding movementbeneath the main plate 71 of outer link 68 and between the side flanges72 thereof. Knob 73 has a pin 74 depending therefrom. Pin 74 extendsthrough the main plate 71 of outer link 68 and through sliding latch 70.It retains the sliding latch in position by means of a washer 76 underthe sliding latch. A sliding latchmounted operating pin 77 extendsupward through a slot 78 in the main plate 71 and engages in a radialslot 79 on the under side of knob 73. By this means, when knob 73 isturned a quarter turn, the sliding latch moves from its retractedposition of FIG. 6 to its extended position in FIGS. 7 and 8. A slot 81in the sliding latch 70 allows the plate 70 to slide without engagementwith the pin 79. In the extended position, the nose of the latch 70' hasa tee slot which engages in complementary structure in its associatedlatchplate. Such suitable complementary structure is seen in thelatchplate in FIGS. 12 and 13.

The lower end of pin 74 has a head 74a thereon which lies next to andengages with head 82a of lock pin 82. Lock pin 82 is secured to thebase; however a portion 83 of the head on pin 74 is removed so that,when sliding latch 70 is in its extended position, pin 74 is unlockedfrom lock pin 82. However, when in the folded position, with slidinglatch 70 retracted, pin 74 is turned to a position where the heads onthe two pins interengage, and outer link 68 is locked down.

In FIGS. 9, 10 and 11, the safety latch of this invention is embodied assafety latch 84. Safety latch 84 has a base 86, intermediate link 88,and outer link 90. Similarly to safety latch 62, sliding latch 92, likelatchplate 70 in safety latch 62, has a latch nose for interengagementwith a suitable latchplate. The sliding latch 92 slides beneath outerlink 90, and it is, preferably moved from the inner, retracted positionto the outer, latching position by means of operation of knob 94. Knob94 is directly coupled by means of a shaft 95 movable along a slot 96 inthe outer link 90 to sliding latch 92; thus knob 94 is simply thrustfrom one position to the other and slides, carrying the sliding latchwith it. As in the previously described embodiments, the intermediatelink 88 is provided with a lock post-accommodating hole 97.

As the sliding latch 92 moves from one terminal position to the other,it is retained by detent spring 99. Furthermore, locking of the outerlink 90 is accomplished by upstanding T-headed lock post 98. When in theretracted position, lock fingers 100 of the sliding latch 92 engagearound lock post 98 to restrain the outer link 90 in the folded, lockedposition when the latch nose is retracted. When the sliding latch 92 isextended, the outer link is unlocked at the same time the nose of thesliding latch engages in the latchplate. Again, unfolding to a limitedextension is possible to limit opening of the door. Y

The safety latch of this invention is further embodies in safety latch102, shown in FIGS. 12, 14 and 15. Safety latch 102 is quite similar tosafety latch 62. It has a base 104, but compared to the base of safetylatch 62,

base 104 is very much larger. In addition to serving as a base forintermediate link 106 which is pivoted thereon on pivot pin 108, itserves also to carry a conventional doorknob structure which terminatesin doorknob 110. The doorknob can carry its own lock, as indicated bylock knob 112. Interiorly of the door, the doorknob operates theconventional latch which engages into latch opening 114 in latchplate116. The latchplate is securely attached to a doorframe by screws 117.

FIGS. 12 through illustrate that any of the safety latch structures canbe incorporated into a base 104 which also has the usual doorknob anddoor latch structures. In this arrangement, it serves as an additionalsafety latch which permits limited opening of the door. Safety latch 102is illustrative of a particular safety latch structure, but any of thesafety latches described above can be equally conveniently employed. Ofcourse, appropriate arrangements of the lockdown structure would benecessary in such cases.

With respect to safety latch 102, sliding latch 118 is slidably mountedunderneath outer link 120 similarly to the structure of safety latch 62.Sliding latch 118 has a latch nose 122 with a key slot 123 therein whichis engageable into a complementary structure 124 in latchplate 116. Thelatch nose 122 can be extended into the complementary slots only whenthe safety latch 102 lies in its folded position. Once extended, theangle between the nose 122 and the slots 124 in the latchplate retainthe nose in the latchplate. Sliding latch 118 is moved from front toback by rotation of operating knob 126 in the same manner as describedwith respect to FIGS. 6 through 8. Locking down of the outer link isaccomplished by lock finger 128 on the rear end of sliding latch 118.When in the folded position, retraction of sliding latch 118 causes lockfinger 128 to pass underneath the adjacent portion 129 of the base tothereby lock the outer link 120 down into position. In this way, thesafety latch 102 is locked down when it is not needed. As the slidinglatch 118 is moved to the extended position, it unlocks the outer link120 at the same time the latch nose 122 engages with its complementaryslot 124 in the latchplate 116.

From the foregoing, it should be evident that there has been describedseveral safety latch constructions in accordance with differentembodiments of the invention, all of which permit opening of a door alimited amount with maximum security.

It should be evident that the materials used to fabricate theembodiments of the invention are not critical and any material generallyconsidered to be suitable for a particular application may be used. Forexample, various parts of the mechanism may be fabricated from brass,brassplated steel, aluminum, and possibly even some synthetic materialsmay be utilized. Also, any suitable manufacturing process, such ascasting, machining, stamping, etc., may be used.

It should also be understood that although several embodiments of theinvention have been described, the invention is susceptible to numerousmodifications and embodiments within the ability of those skilled in theart and without the exercise of the inventive faculty.

6 For example, the latchplate may be mounted on the door and the linkmechanism mounted on the doorframe. Accordingly, all such modificationsand embodiments are deemed to be within the spirit, scope andcontemplation of this invention.

I claim:

1. A safety latch for limiting the amount of opening of a door memberwith respect to a doorframe member, said safety latch comprising:

a base for mounting on one of the door members adjacent the edgethereof;

an intermediate link pivotally mounted on said base;

an outer link pivotally mounted on said intermediate link, said base,said intermediate link, and said outer link being configured so thatsaid outer link lies adjacent said base when said outer link is in itsretracted position, and said outer link pivots outward away from saidbase to extend past said edge when in its extended position; latchmovably mounted on said outer link; stationary latchplate for mountingon the other door member, said latch having a nose engageable in a latchslot in said latchplate only when said outer link is in its retractedposition and said nose remaining latched in-said latch slot as the dooropens and said links unfold to a maximum limit position which limits themaximum door opening.

2. The safety latch of claim 1 wherein said outer link has a top paneland said latch is movably mounted on said outer link beneath said toppanel.

3. The safety latch of claim 2 wherein a knob is positioned on the frontof said outer link, said knob being connected to said latch to move saidlatch from its unlatched to its latched position.

4. The safety latch of claim 3 wherein said latch nose is a tee shapednose for engagement in a tee slot in said latchplate, said latch furtherhaving a latch tongue thereon for engagement in the tee slot in saidlatchplate, said latch being pivotally mounted so that said tongue andsaid latch nose can be selectively engaged in said latchplate.

5. The safety latch of claim 3 wherein a lock pin interconnects saidbase and said outer link when said latch is in its retracted position.

6. The safety latch of claim 3 wherein said latch is a sliding latchslidably positionable from an extended position wherein its latch noseengages in an engagement slot in said latchplate to a retracted,unengaged posi- Hon.

7. The safety latch of claim 6 wherein said base carries locking meansthereon and said sliding latch engages said locking means for lockingsaid outer link in the retracted position.

8. The safety latch of claim 7 wherein said base is a portion of adoorknob-mounting structure.

9. The safety latch of claim 3 wherein said base is a portion of adoorknob-mounting structure.

10. The safety latch of claim 1, also comprising spring means associatedwith said latch and said outer link for indexing and biasing said latch.

1. A safety latch for limiting the amount of opening of a door member with respect to a doorframe member, said safety latch comprising: a base for mounting on one of the door members adjacent the edge thereof; an intermediate link pivotally mounted on said base; an outer link pivotally mounted on said intermediate link, said base, said intermediate link, and said outer link being configured so that said outer link lies adjacent said base when said outer link is in its retracted position, and said outer link pivots outward away from said base to extend past said edge when in its extended position; a latch movably mounted on said outer link; a stationary latchplate for mounting on the other door member, said latch having a nose engageable in a latch slot in said latchplate only when said outer link is in its retracted position and said nose remaining latched in said latch slot as the door opens and said links unfold to a maximum limit position which limits the maximum door opening.
 2. The safety latch of claim 1 wherein said outer link has a top panel and said latch is movably mounted on said outer link beneath said top panel.
 3. The safety latch of claim 2 wherein a knob is positioned on the front of said outer link, said knob being connected to said latch to move said latch from its unlatched to its latched position.
 4. The safety latch of claim 3 wherein said latch nose is a tee shaped nose for engagement in a tee slot in said latchplate, said latch further having a latch tongue thereon for engagement in the tee slot in said latchplate, said lAtch being pivotally mounted so that said tongue and said latch nose can be selectively engaged in said latchplate.
 5. The safety latch of claim 3 wherein a lock pin interconnects said base and said outer link when said latch is in its retracted position.
 6. The safety latch of claim 3 wherein said latch is a sliding latch slidably positionable from an extended position wherein its latch nose engages in an engagement slot in said latchplate to a retracted, unengaged position.
 7. The safety latch of claim 6 wherein said base carries locking means thereon and said sliding latch engages said locking means for locking said outer link in the retracted position.
 8. The safety latch of claim 7 wherein said base is a portion of a doorknob-mounting structure.
 9. The safety latch of claim 3 wherein said base is a portion of a doorknob-mounting structure.
 10. The safety latch of claim 1, also comprising spring means associated with said latch and said outer link for indexing and biasing said latch. 